JP5678722B2 - Oil temperature estimation device - Google Patents

Description

  The present invention relates to an oil temperature estimation device that estimates the temperature of hydraulic oil for an internal combustion engine, for example, based on the temperature of engine cooling water.

  Some internal combustion engines are equipped with a hydraulically driven valve timing variable mechanism that varies the opening and closing timing (hereinafter referred to as valve timing) of intake valves and exhaust valves for the purpose of reducing fuel consumption and improving exhaust properties. is there. In such an internal combustion engine, when the temperature of the hydraulic fluid of the internal combustion engine (hereinafter referred to as hydraulic fluid temperature) is low, such as during cold start, the viscosity of the hydraulic fluid is high, and the variable valve timing mechanism may not be driven properly. There is.

Therefore, conventionally, the hydraulic oil temperature is directly detected by the oil temperature sensor, and when the hydraulic oil temperature is equal to or lower than the determination temperature, the driving of the variable valve timing mechanism is limited.
For example, as described in Patent Document 1, the oil temperature sensor is omitted for the purpose of reducing the number of parts, and the operation is based on the temperature of the engine cooling water (hereinafter, cooling water temperature) detected by the water temperature sensor. There is an oil temperature estimation device that calculates an estimated value of oil temperature (hereinafter, oil temperature estimated value).

  In the oil temperature estimating device described in Patent Document 1, the cooling water temperature at the time of starting the engine (hereinafter referred to as the water temperature at the time of starting) is regarded as the hydraulic oil temperature at the time of starting the engine (hereinafter referred to as the oil temperature at the time of starting) and The estimated oil temperature is calculated based on the oil temperature and the engine speed and engine load. Specifically, considering that the higher the engine speed and the higher the engine load, the greater the amount of heat generated by the internal combustion engine per unit time, the hydraulic oil based on the integrated value of the engine speed and engine load. The amount of increase in temperature is being sought.

JP-A-10-227235

  Incidentally, the oil temperature estimation device described in Patent Document 1 calculates an oil temperature estimated value based on an integrated value of an engine rotational speed and an engine load. Therefore, not only the calculation mode of the estimated oil temperature is complicated, but also the calculation accuracy is low.

  The present invention has been made in view of such circumstances, and its purpose is to calculate an oil temperature estimated value based on a cooling water temperature, and the oil temperature estimated value can be easily and accurately calculated. The object is to provide an oil temperature estimating device.

Hereinafter, means for solving the above-described problems and the effects thereof will be described.
According to the first aspect of the present invention, the estimated oil temperature, which is an estimated value of the temperature of the hydraulic oil that rises due to heat received from the internal combustion engine, is converted into a coolant temperature detected by a coolant temperature sensor that detects the temperature of the engine coolant. An oil temperature estimation device including a calculation unit that calculates based on a volatile memory that stores an estimated oil temperature value calculated by the calculation unit, and the calculation unit is configured to start an engine by a key operation of a driver. while the starting oil temperature is the temperature of the hydraulic fluid of starting water temperature is a cooling water temperature when the engine start during the engine start, when restarting from the automatic stop, finally volatilized during the previous engine operation The estimated oil temperature stored in the memory is used as the starting oil temperature, and the estimated oil temperature is calculated based on the starting oil temperature and the degree of deviation between the starting water temperature and the current cooling water temperature. It is said. According to the second aspect of the present invention, the estimated oil temperature, which is an estimated value of the temperature of the hydraulic oil that rises due to heat received from the internal combustion engine, is detected by a water temperature sensor that detects the temperature of engine cooling water. An oil temperature estimation device including a calculation unit that calculates based on a water temperature, and includes a volatile memory that stores an estimated oil temperature value calculated by the calculation unit, the volatile memory being operated by a driver's key operation When the engine is stopped, power is cut off and the stored information is lost.On the other hand, when the engine is stopped due to automatic stop, the power is continued and the stored information is retained. When the estimated oil temperature is not stored in the volatile memory, the starting water temperature that is the cooling water temperature at the time of starting the engine is used as the starting oil temperature that is the temperature of the working oil at the time of starting the engine. , Engine start When the estimated oil temperature value is stored in the volatile memory, the estimated oil temperature value stored last in the volatile memory during the previous engine operation is used as the starting oil temperature, The gist is to calculate the estimated oil temperature based on the degree of deviation between the starting water temperature and the current cooling water temperature.

  Since the cooling water temperature and the hydraulic oil temperature are equal at the first engine start, the start-up water temperature can be regarded as the start-up oil temperature. A predetermined correspondence relationship is established between the amount of change in the hydraulic oil temperature from the start of the engine start to the present and the degree of deviation between the start-up water temperature and the current cooling water temperature. For example, when the hydraulic oil temperature is within a predetermined range of 0 degrees or less, a correspondence relationship is established in which the hydraulic oil rises in temperature by a second predetermined value while the coolant rises in temperature by a first predetermined value. For this reason, according to the above configuration, when the first engine start-up, that is, when the estimated oil temperature is not stored in the volatile memory, the start-up water temperature is set to the start-up oil temperature, and the start-up oil temperature Based on the degree of deviation between the starting water temperature and the current cooling water temperature, the estimated oil temperature can be easily calculated with high accuracy.

  On the other hand, for example, when the internal combustion engine is automatically stopped and then restarted, the cooling water temperature and the hydraulic oil temperature are different from each other, and the starting water temperature cannot be regarded as the starting oil temperature. In this regard, according to the above configuration, when the estimated oil temperature is stored in the volatile memory at the time of the restart, the estimated oil temperature stored last in the previous engine operation is used as the starting oil temperature. At the same time, the estimated oil temperature can be easily calculated with high accuracy based on the starting oil temperature and the degree of deviation between the starting water temperature and the current cooling water temperature.

Accordingly, the estimated oil temperature value is calculated based on the coolant temperature, and the estimated oil temperature value can be easily calculated with high accuracy.
The oil temperature estimation device according to claim 1 or 2 can be embodied with an aspect in which, as in the invention according to claim 3 , the hydraulic oil is hydraulic oil of an internal combustion engine. As such hydraulic oil, in addition to the internal combustion engine hydraulic oil whose temperature rises due to direct heat reception from the internal combustion engine, automatic oil whose temperature rises due to indirect heat reception from the internal combustion engine by exchanging heat with engine cooling water. There is hydraulic fluid for the transmission.

According to a third aspect of the present invention, in the oil temperature estimation device according to the fourth aspect of the invention, the calculation unit multiplies the deviation between the starting water temperature and the current cooling water temperature by a predetermined coefficient to thereby calculate the engine temperature. The embodiment can be embodied in such a manner that the amount of change in the temperature of the hydraulic oil from the start to the present is calculated, and the sum of the amount of change and the oil temperature at the start is calculated as the estimated oil temperature. . In this case, the estimated oil temperature can be easily calculated. In addition, as described above, when the correspondence relationship is established such that the temperature of the hydraulic oil rises by the second predetermined value while the temperature of the cooling water rises by the first predetermined value, the first predetermined value and It is desirable to set the predetermined coefficient based on the ratio with the second predetermined value.

The block diagram which shows schematic structure centering on an electronic controller about one Embodiment of the oil temperature estimation apparatus which concerns on this invention. The graph which shows an example of the relationship between cooling water temperature and hydraulic oil temperature. The graph which shows an example of the relationship between cooling water temperature and hydraulic oil temperature. The flowchart which shows the procedure of the calculation process of the oil temperature estimated value in the embodiment. The graph which shows an example of the relationship between cooling water temperature and hydraulic oil temperature.

  Hereinafter, with reference to FIG. 1 to FIG. 4, the oil temperature estimation device according to the present invention is embodied as a device for calculating an estimated value (hereinafter referred to as an oil temperature estimated value) of the temperature of hydraulic oil in a vehicle-mounted internal combustion engine. The embodiment will be described in detail. In addition, the vehicle of this embodiment is a hybrid vehicle provided with an internal combustion engine and a motor as a driving source for wheels. The internal combustion engine is a water-cooled gasoline engine.

As shown in FIG. 1, the internal combustion engine 5 is equipped with a hydraulically driven variable valve timing mechanism 6 for changing the valve timing of intake valves and exhaust valves.
The electronic control device 1 executes various controls of the internal combustion engine 5, a CPU that executes various arithmetic processes related to engine control, and a ROM that is a nonvolatile memory in which programs and data necessary for the control are stored It has. In addition, an SRAM 2 which is a volatile memory in which CPU calculation results and the like are temporarily stored, an input port and an output port for inputting / outputting signals to / from the outside, and the like are provided.

In the SRAM 2, information can be stored while power is supplied to the SRAM 2, but the stored information is lost when the power is stopped.
The electronic control device 1 performs various controls such as engine start control, fuel injection control, throttle control, automatic stop and restart control, and valve timing control.

  The electronic control device 1 receives signals from various sensors for grasping the running state of the vehicle and the engine operating state. The various sensors include, for example, an accelerator sensor that detects the amount of depression of the accelerator pedal, a brake sensor that detects the depression state of the brake pedal, a throttle sensor that detects the opening degree of the throttle valve, a rotation speed sensor that detects the engine rotation speed, and An intake air amount sensor for detecting the intake air amount is provided. Further, a water temperature sensor 3 for detecting a cooling water temperature THWn that is a temperature of the engine cooling water, an ignition switch, and the like are provided. The internal combustion engine is not provided with an oil temperature sensor that directly detects the temperature of the hydraulic oil.

Next, an example of the relationship between the cooling water temperature and the hydraulic oil temperature will be described.
Both the hydraulic oil and the cooling water of the internal combustion engine 5 rise in temperature due to heat received from the internal combustion engine 5. Here, a predetermined correspondence relationship is established between the change amount of the hydraulic oil temperature after the start of the engine is started and the change amount of the cooling water temperature.

FIG. 2 shows the relationship between the cooling water temperature and the hydraulic oil temperature until the engine operation is started when the cooling water temperature and the hydraulic oil temperature are both minus 30 degrees and the cooling water temperature reaches 30 degrees.
As shown by a solid line in FIG. 2, when the hydraulic oil temperature is within a predetermined range of 0 degrees or less, for example, a correspondence relationship is established in which the hydraulic oil rises by 5 degrees while the coolant temperature rises by 10 degrees. . Therefore, a value obtained by dividing the increase amount of the hydraulic oil temperature by the corresponding increase amount of the cooling water temperature is a predetermined value (in the present embodiment, “0.5”). The predetermined value varies depending on the displacement of the internal combustion engine.

The cooling water temperature and the hydraulic oil temperature are equal when the engine is started for the first time after the engine is stopped for a long time, that is, when the engine is started by key operation by the driver. Therefore, the cooling water temperature at the time of starting the engine (hereinafter referred to as the starting water temperature THWstrtn) can be regarded as the hydraulic oil temperature at the time of starting the engine (hereinafter referred to as the starting oil temperature TOstrtn). Therefore, at the time of the first engine start, that is, when the estimated oil temperature value TOestn-1 is not stored in the SRAM 2, the estimated oil temperature value TOestn can be calculated from the following equation (1).

TOestn = THWstrtn + K × (THWn−THWstrtn) (1)

The transition of the estimated oil temperature value TOestn calculated in this way is shown by a one-dot chain line in FIG.

  By the way, when the coolant temperature and the hydraulic oil temperature are equal as in the first engine start, the start-up water temperature THWstrtn can be regarded as the start-up oil temperature TOstrtn. However, as described above, when the hydraulic oil temperature is within a predetermined range of 0 degrees or less, the coolant temperature rises earlier than the hydraulic oil temperature. Therefore, the internal combustion engine 5 is automatically stopped during the warming-up of the internal combustion engine 5 and restarted immediately thereafter. When the oil temperature estimated value TOestn is calculated from the above equation (Equation 1) thereafter, The following problems arise.

  That is, as shown by a broken line in FIG. 3, when the internal combustion engine 5 is automatically stopped and restarted when the coolant temperature is minus 20 degrees and the hydraulic oil temperature is minus 25 degrees, for example, the starting oil temperature TOstrtn As a starting water temperature THWstrtn, that is, minus 20 degrees is set. Therefore, although the actual hydraulic oil temperature is minus 25 degrees, a temperature 5 degrees higher than this is set as the oil temperature estimated value TOestn, and the estimated oil temperature value TOestn is higher than the actual hydraulic oil temperature. Become. As the automatic stop and restart are repeated, the difference between the estimated oil temperature value TOestn and the actual hydraulic oil temperature increases. When the coolant temperature slightly exceeds 0 degrees, the actual hydraulic oil temperature Despite being about minus 15 degrees, the estimated oil temperature value TOestn exceeds 0 degrees.

  As a result, for example, when the estimated oil temperature value TOestn is 0 degrees or less, the viscosity of the working oil is high, and the valve timing variable mechanism 6 may not be driven appropriately. If the TOestn is higher than 0 degrees, the drive restriction is released in the configuration in which the drive restriction is released.

  Considering such an error in the estimated oil temperature value TOestn, it is conceivable to limit the drive of the variable valve timing mechanism 6 until the coolant temperature THWn reaches a relatively high determination temperature (for example, 60 degrees). However, when the internal combustion engine 5 is not automatically stopped and restarted and the difference between the estimated oil temperature value TOestn and the actual hydraulic oil temperature is small, the following problem occurs. That is, the coolant temperature THWn is lower than the above-described determination temperature, even though the actual hydraulic oil temperature rises and is included in the temperature range in which the valve timing variable mechanism 6 can be appropriately driven. In addition, the drive limitation of the variable valve timing mechanism 6 is continued unnecessarily.

Therefore, in this embodiment, when the internal combustion engine 5 is restarted, that is, when the oil temperature estimated value TOestn-1 is stored in the SRAM 2, the oil temperature estimated value TOestn-1 stored last during the previous engine operation is started. The oil temperature estimated value TOestn is calculated from the following equation (2), together with the hourly oil temperature TOstrtn.

TOestn = TOestn−1 + K × (THWn−THWstrtn) (2)

The transition of the estimated oil temperature value TOestn calculated in this way is shown by a one-dot chain line in FIG. The actual hydraulic oil temperature is shown by a solid line in FIG.

  Incidentally, as described above, the SRAM 2 stores the estimated oil temperature value TOestn-1 stored last time during the previous engine operation, as long as the power supply to itself is continued. On the other hand, since the energization is stopped immediately before the first engine start by the driver's key operation or the like, the oil temperature estimated value TOestn-1 stored last during the previous engine operation is cleared.

  Next, the procedure for calculating the oil temperature estimated value TOestn will be described with reference to the flowchart of FIG. Note that the series of processing shown in FIG. 4 is repeatedly executed at predetermined intervals by the electronic control unit 1 during engine operation.

  In this series of processes, first, in step S1, it is determined whether or not the estimated oil temperature value TOestn-1 is cleared from the SRAM 2, that is, whether or not it is the first engine start time. Here, when the estimated oil temperature value TOestn-1 is cleared (step S1: “YES”), the process proceeds to step S2, and the starting water temperature THWstrtn is set to the starting oil temperature TOstrtn.

  On the other hand, when the estimated oil temperature value TOestn-1 is not cleared (step S1: “NO”), that is, at the time of restart after automatic stop, the process proceeds to step S3, where the oil temperature is estimated to the starting oil temperature TOstrtn. Set the value TOestn-1.

  When the starting oil temperature TOstrtn is thus set, the process proceeds to step S4, and the estimated oil temperature value TOestn is calculated based on the starting oil temperature TOstrtn, the coefficient K, the current cooling water temperature THWn, and the starting water temperature THWstrtn. Then, the process proceeds to step S5, where the calculated estimated oil temperature value TOestn is stored in the SRAM 2, and this series of processes is temporarily terminated.

  Incidentally, as shown in FIG. 5, when the hydraulic oil temperature is 0 ° C. or higher and the coolant temperature is 40 ° C. or higher, the actual hydraulic oil temperature shown by the solid line is higher than the estimated oil temperature value TOestn shown by the alternate long and short dash line. . However, when the hydraulic oil temperature is 0 ° C. or higher, there is no problem in performing valve timing control due to the oil temperature estimated value TOestn being calculated lower than the actual hydraulic oil temperature.

The electronic control device 1 functions as an oil temperature estimation device and a calculation unit according to the present invention.
According to the oil temperature estimation apparatus according to the present embodiment described above, the following effects can be obtained.

  (1) The electronic control unit 1 calculates an estimated oil temperature value TOestn, which is an estimated value of the temperature of the working oil of the internal combustion engine 5, based on the cooling water temperature detected by the water temperature sensor 3. Moreover, SRAM2 which memorize | stores the calculated oil temperature estimated value TOestn is provided. When the estimated oil temperature value TOestn-1 is not stored in the SRAM 2, the starting water temperature THWstrtn, which is the cooling water temperature at the time of starting the engine, is used as the starting oil temperature, which is the temperature of the working oil at the time of starting the engine. Let it be TOstrtn. Further, when the estimated oil temperature value TOestn-1 is stored in the SRAM 2, the estimated oil temperature value TOestn-1 last stored during the previous engine operation is set as the starting oil temperature TOstrtn. Then, by multiplying the deviation ΔTHW (= THWn−THWstrtn) between the start-time water temperature THWstrtn and the current coolant temperature THWn by a predetermined coefficient K, the amount of increase in hydraulic oil temperature ΔTO from the start of the engine start to the present Is calculated, and an addition value of the amount of increase ΔTO and the starting oil temperature TOstrtn is calculated as an estimated oil temperature value TOestn. According to such a configuration, the estimated oil temperature value TOestn is calculated based on the cooling water temperature, and the estimated oil temperature value TOestn is obtained even when the cooling water temperature is deviated from the hydraulic oil temperature when the engine is started. Can be calculated accurately and easily.

  (2) The electronic control unit 1 restricts the drive of the hydraulically driven valve timing variable mechanism 6 based on the calculated estimated oil temperature value TOestn. According to such a configuration, the driving of the variable valve timing mechanism 6 is limited based on the estimated oil temperature value TOestn calculated with high accuracy. For this reason, in the configuration for calculating the estimated oil temperature value TOestn based on the coolant temperature, the drive of the hydraulically driven valve timing variable mechanism 6 is unnecessarily limited, that is, the valve timing control is unnecessarily limited. This can be suppressed.

In addition, the oil temperature estimation apparatus according to the present invention is not limited to the configuration exemplified in the above-described embodiment, and may be implemented as, for example, the following form that is appropriately changed.
The internal combustion engine to which the present invention is applied is not limited to a gasoline engine, but may be applied to, for example, a diesel engine as long as it is a water-cooled internal combustion engine.

In the above embodiment, the present invention is applied to the internal combustion engine 5 that is applied to a hybrid vehicle. However, the present invention may be applied to an engine that includes only the internal combustion engine as a drive source for the vehicle. . That is, Ru challenge in the same manner with raw Ji obtained shown in the above embodiment as long as it performs the automatic stop and restart even the internal combustion engine. Therefore, by applying the present invention, an effect according to the effect of the above embodiment can be achieved.

  In the above embodiment, the drive of the hydraulically driven valve timing variable mechanism 6 is limited based on the calculated estimated oil temperature value TOestn. However, the control based on the estimated oil temperature value TOestn is limited to this. It is not a thing. In short, if the oil temperature estimated value calculated when the hydraulic oil temperature is equal to or lower than the first predetermined temperature (0 degrees in the above embodiment) becomes a problem, it can be applied to any control target. . Therefore, for example, the estimated oil temperature value TOestn may be used for the control of a hydraulically driven valve lift variable mechanism that varies the valve lift of the intake valve and the exhaust valve.

  -The calculation method of oil temperature estimated value TOestn is not limited to the thing using the primary formula (Formula (1) and Formula (2)) illustrated in the said embodiment. In short, it may be calculated based on the starting oil temperature TOstrtn and the degree of deviation between the starting water temperature THWstrtn and the current cooling water temperature THWn, and may be derived using a map or the like. Further, when the hydraulic oil temperature is higher than the first predetermined temperature, the estimated oil temperature value TOestn may be calculated using a function other than the linear expression, for example, a quadratic expression.

  In the above embodiment, the oil temperature estimation device is embodied as one that estimates the temperature of the hydraulic oil of the internal combustion engine 5, but the oil temperature estimation device according to the present invention is not limited to this, and other examples include, for example, It can also be embodied to estimate the temperature of the hydraulic fluid (ATF) of the automatic transmission. In an automatic transmission, ATF is generally configured to exchange heat with engine cooling water. Therefore, ATF can be said to be hydraulic fluid whose temperature rises due to indirect heat received from an internal combustion engine.

1 ... electronic control unit, 2 ... SRAM (volatile memory), 3 ... water temperature sensor, 5 ... internal combustion engine, 6 ... variable valve timing mechanism.

Claims (4)

Oil provided with a calculating unit that calculates an estimated oil temperature, which is an estimated value of the temperature of hydraulic oil that rises due to heat received from the internal combustion engine, based on a coolant temperature detected by a water temperature sensor that detects the temperature of the engine coolant. A temperature estimation device,
A volatile memory for storing the estimated oil temperature value calculated by the calculation unit;
The calculating unit, when the engine is started by the driver's key operation, while the starting oil temperature is the temperature of the hydraulic fluid when the starting temperature is a cooling water temperature of the engine start during the engine starting, the automatic stop When restarting from, the estimated oil temperature stored in the volatile memory at the last engine operation is used as the starting oil temperature, and the difference between the starting oil temperature, the starting water temperature, and the current cooling water temperature. An oil temperature estimation device that calculates an estimated oil temperature value based on the degree. A calculation unit is provided that calculates an estimated oil temperature, which is an estimated value of the temperature of hydraulic oil that rises due to heat received from the internal combustion engine, based on a coolant temperature detected by a water temperature sensor that detects the temperature of the engine coolant. An oil temperature estimation device,
A volatile memory for storing the estimated oil temperature value calculated by the calculation unit;
In the volatile memory, when the engine is stopped by the driver's key operation, the power is cut off and the stored information is lost. On the other hand, when the engine is stopped by the automatic stop, the power is continued and the stored information is retained. Is,
When the estimated oil temperature value is not stored in the volatile memory at the time of starting the engine , the calculating unit calculates the starting water temperature that is the cooling water temperature at the time of starting the engine by the temperature of the hydraulic oil at the time of starting the engine. there while the starting oil temperature, when the estimated value oil temperature in the volatile memory at the time of engine startup is stored, starting at the end in the volatile memory estimated oil temperature value stored in the last time of engine operation An oil temperature estimation device characterized in that an oil temperature estimation value is calculated based on the starting oil temperature and the degree of deviation between the starting water temperature and the current cooling water temperature. In the oil temperature estimating device according to claim 1 or 2 ,
The hydraulic oil is an internal combustion engine hydraulic oil. In the estimated oil temperature according to claim 3 ,
The calculation unit calculates the amount of change in the temperature of the hydraulic oil from the start of the engine start to the present by multiplying a deviation between the start-up water temperature and the current cooling water temperature by a predetermined coefficient, and the change amount An oil temperature estimation device that calculates an added value of the oil temperature at start and the oil temperature at the start as an estimated oil temperature.

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